INVESTIGATIONS
Active case files
Active6
Critical2
High2
Watch2
$ avoided$22.6k
CRITICALREMEDIATING
inv-2412opened 2026-05-06 03:14:00 · 22m agoFatigue cluster — Final Assembly night shift
5 operators on Line L1-FA crossed the 80-fatigue threshold within 11 minutes of each other on graveyard. Pattern doesn't match prior cluster signatures.
OWNER
Fatigue Watcher (auto)
COLLABORATORS
sup-aviation-lead-3, ops-manager-east
TRIGGER
fatigue_cluster_density · Fatigue Watcher
Threshold:
>= 5 operators in 15 minLinked entities
8 entities — all typed against the ontology
person·PRSN-1284Sara Mitchell
subject (FG-87)
person·PRSN-1410James Okonkwo
subject (FG-83)
person·PRSN-872Maria Sanchez
subject (FG-81)
person·PRSN-1102Daniel Kim
subject (FG-80)
person·PRSN-1445Aisha Patel
subject (FG-82)
line·L1-FAFinal Assembly · Line 1
physical context
shift·SHFT-9012Mon graveyard 22:00–06:00
active shift
department·DEPT-OPS-NIGHTOperations · Night
owning unit
Hypothesis tree
Confidence-weighted; auto-investigators add and prune
H1LEADINGconfidence 78%Three consecutive 12h shifts with <8h rest — accumulating sleep debt.
evidence:
e1e2e6H2ACTIVEconfidence 62%Heat-stress proxy: HVAC failure logged 02:48 → ambient up 3.2°C above setpoint.
evidence:
e3e4H3SUPPORTINGconfidence 41%Substituted operators on assist roles — different pacing than primary crew.
evidence:
e5H4RULED OUTconfidence 18%Sensor drift in wearable batch 412.
evidence:
e7Evidence
7 artefacts — all linked back to source
e1FG-87 for PRSN-1284 (Sara Mitchell) — exceeded threshold by 7 points.
SIGNAL·Fatigue Watcher·03:14:08
e2Avg rest gap last 72h: 7.4h vs target 9h+ across the 5 subjects.
METRIC·WFM rest table
e3AHU-3 fan VFD fault — supply temp drift from 21.2°C to 24.4°C over 18 min.
SIGNAL·BMS HVAC monitor·02:48:21
e4Wet-bulb proxy from 19.6°C → 22.1°C in cell L1-FA between 02:55 and 03:14.
METRIC·Plant historian
e5Reassigned 2 from Line L4-STMP to L1-FA (skill-match 0.91, fatigue floor 35).
PRIOR DECISION·Decisions Ledger·Yesterday
e6Three 12h consecutive nights raises near-miss rate ~2.3× (NIOSH 2019 review).
EXTERNAL·OSHA fatigue lit
e7Batch 412 calibration check yesterday: 0.4-point drift, well within ±2 tolerance.
METRIC·Wearable QA
Timeline
Append-only; every entry is a decision-ledger row
03:14:08TRIGGERFatigue Watcher5-operator fatigue cluster detected on L1-FA night shift.
03:14:11NOTEAuto-investigatorCase INV-2412 opened, severity CRITICAL.
03:15:42EVIDENCEAuto-investigatorCross-referenced HVAC log; AHU-3 VFD fault logged 02:48.
03:18:01HYPOTHESISAuto-investigatorH2 promoted from supporting → active (heat stress proxy).
03:21:17NOTEsup-aviation-lead-3Confirms cell felt warm during walk-down. Logging informally.
03:24:33RECOMMENDATIONFatigue GuardianPropose 30-min staggered breaks + swap 2 of 5 to cool-down assist.
03:25:12RECOMMENDATIONMaintenance OptimizerDispatch maintenance for AHU-3 VFD; ETA 25 min.
03:26:48ACTIONops-manager-eastApproved staggered breaks + 2 swaps. AHU-3 dispatch confirmed.
03:32:04NOTEops-manager-eastBriefing sent to incoming shift lead at 04:00 handoff.
Recommendations
From the ontology's Action Library — typed, traceable, reversible
Stagger 30-min breaks across the 5 subjects
shiftEXECUTEDReduces cumulative active-on-shift time, distributes recovery.
proposed by
Fatigue GuardianReassign PRSN-1102 + PRSN-1445 to cool-down / assist roles for 90 min
shiftEXECUTEDTwo highest-fatigue with substitution earlier today; assist roles 30% lower workload.
proposed by
Fatigue GuardianDispatch maintenance for AHU-3 VFD fault (priority P1)
maintenance_taskEXECUTEDHeat-stress hypothesis is high-confidence; restoring HVAC removes the upstream cause.
proposed by
Maintenance OptimizerCompose handoff brief for 06:00 day-shift lead
documentAPPROVEDDay-shift inherits the operators; needs full context to prevent recurrence.
proposed by
Briefing ComposerOutcome
$4,200 avoidedAHU-3 restored at 03:51. Cell temp back to setpoint by 04:08. Zero reported near-misses. 2 of 5 subjects opted to leave early (paid). Estimated cost-avoided $4,200 in incident risk + 7.4h fatigue debt cleared.